Location positioning of a mobile station (MS) may be useful for emergency situation management, surveillance, value-added services, and location-smart applications.
Several network-based MS positioning methods have been proposed. Some triangulation systems may utilize multiple base stations (BSs) in communication with the MS. The system may measure a differential delay between a transmission from the MS and a receipt of the transmission at each of two or more BSs. This technique may assume that the multiple base stations are listening to the signal transmitted by the MS. That is, receive diversity may be required. Thus, the MS must actively participate in the location positioning procedure.
Another widely-used technique utilizes the global positioning system (GPS). This technique requires GPS hardware in the MS, thus adding to the cost and complexity of the device. Furthermore, GPS requires a direct-line-of-sight path between the mobile device and the GPS satellites, and thus restricts the GPS technique largely to an outdoor environment.
Therefore, a need exists in the art for an MS localization system that requires neither macro diversity nor active transmission by the MS for localization operations.